Method and system for mitigating interference among femtocells via intelligent channel selection

ABSTRACT

Aspects of a method and system for mitigating interference among femtocells via intelligent channel selection are provided. In this regard, signals which may interfere with cellular communications between a femtocell and a cellular communication device may be detected via the femtocell. Based on the detection, the femtocell may be configured to transmit and/or receive signals on one or more frequencies and/or channels. The one or more frequencies and/or channels may be determined in the femtocell and/or in a network management entity. Detecting interfering signals and configuring the one or more femtocells may occur periodically, upon installation of a femtocell, upon power-up of a femtocell, and/or upon command from a network administrator. The results of the detection may be communicated to one or more other femtocells and/or to a network management entity.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

Not applicable

FIELD OF THE INVENTION

Certain embodiments of the invention relate to communication networks.More specifically, certain embodiments of the invention relate to amethod and system for mitigating interference among femtocells viaintelligent channel selection.

BACKGROUND OF THE INVENTION

A femtocell may be placed in a customer's residence or in a smallbusiness environment, for example. Femtocells may be utilized foroff-loading macro radio network facilities, improving coverage locallyin a cost-effective manner, and/or implementing home-zone services toincrease revenue. Femtocells, like macro base stations, may be enabledto connect “standard” phones to a cellular provider's network by aphysical broadband connection which may be a digital subscriber line(DSL) connection and/or a cable connection, for example. Since thetraffic between a customer's premises femtocell equipment and theoperator's network may be traversing a public network, the traffic mayhave to be secured.

A handover mechanism between femtocells and between femtocells and oneor more cellular provider's networks enables operation in private andpublic areas including indoor and outdoor environments. The capacity ofa femtocell may be adequate to address a typical family use modelsupporting two to four simultaneous voice calls and/or data, forexample.

An important characteristic of femtocells is their ability to controlaccess. In an open access scenario, any terminal and/or subscriber maybe allowed to communicate with the femtocell. Accordingly, the femtocellusage may resemble that of a macrocellular system. In a closed accessscenario, the femtocell may serve a limited number of terminals and/orsubscribers that may be subscribed to a given cellular base station. Inthis regard, the cellular base station may be perceived as beingdeployed for private usage.

A regulatory issue with regard to femtocells is that they use licensedfrequencies that radiate at a very low power in a controlledenvironment. It may be likely that they may not require a license from alocal authority, as macrocellular base stations do. An additionalregulatory issue may arise from the relationship between a femtocelloperator and a broadband services operator. One possible scenario mayinclude the broadband operator being unaware of the existence of afemtocell operator. Conversely, the broadband operator and femtocelloperator may have an agreement or they may be the same operator, forexample.

Femtocells need to be scalable, easily integrated, and robust enough tohandle interference and support synchronization. Interference betweenfemtocells may be an issue for femtocell deployments based on widebandtechnologies such as WCDMA, for example, because initial operatordeployments may use the same frequency for both the femtocell and themacrocellular networks or due to the proximity of femtocell basestations in dense urban areas.

There are a plurality of design models for deployment and integration offemtocells, for example, an IP based lu-b interface, a sessioninitiation protocol (SIP) based approach using an lu/A interface, use ofunlicensed spectrum in a technique known as unlicensed mobile access(UMA) and/or use of IP multimedia subsystem (IMS) voice call continuity(VCC), for example.

In an lu-b model based femtocell deployment approach, femtocells may befully integrated into the wireless carrier's network and may be treatedlike any other remote node in a network. The lu-b protocol may have aplurality of responsibilities, such as the management of commonchannels, common resources, and radio links along with configurationmanagement, including cell configuration management, measurementhandling and control, time division duplex (TDD) synchronization, and/orerror reporting, for example. In lu-b configurations, mobile devices mayaccess the network and its services via the Node B link, and femtocellsmay be treated as traditional base stations.

In a SIP based femtocell deployment approach, a SIP client, embedded inthe femtocell may be enabled to utilize SIP to communicate with theSIP-enabled mobile switching center (MSC). The MSC may perform theoperational translation between the IP SIP network and the traditionalmobile network, for example.

In a UMA based femtocell deployment approach, a generic access network(GAN) may offer an alternative way to access GSM and GPRS core networkservices over broadband. To support this approach, a UMA NetworkController (UNC) and protocols that guarantee secure transport ofsignaling and user traffic over IP may be utilized. The UNC may beenabled to interface into a core network via existing 3GPP interfaces,for example, to support core network integration of femtocell basedservices by delivering a standards based, scalable IP interface formobile core networks.

In an IMS VCC based femtocell deployment approach, VCC may provide for anetwork design that may extend an IMS network to include cellularcoverage and address the handoff process. The IMS VCC may be designed toprovide seamless call continuity between cellular networks and anynetwork that supports VoIP, for example. The VCC may also provide forinteroperability between GSM, UMTS, and CDMA cellular networks and anyIP capable wireless access network, for example. The IMS VCC may alsosupport the use of a single phone number or SIP identity and may offer abroad collection of functional advantages, for example, support formultiple markets and market segments, provisioning of enhanced IMSmultimedia services, including greater service personalization andcontrol, seamless handoff between circuit-switched and IMS networks,and/or access to services from any IP device. Further limitations anddisadvantages of conventional and traditional approaches will becomeapparent to one of skill in the art, through comparison of such systemswith some aspects of the present invention as set forth in the remainderof the present application with reference to the drawings.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present invention asset forth in the remainder of the present application with reference tothe drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method is provided mitigating interference amongfemtocells via intelligent channel selection, substantially as shown inand/or described in connection with at least one of the figures, as setforth more completely in the claims.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a diagram illustrating an exemplary cellular network, inaccordance with an embodiment of the invention.

FIG. 1B is a diagram illustrating cellular communication with via afemtocell, in accordance with an embodiment of the invention.

FIG. 1C is a diagram illustrating an exemplary block diagram of afemtocell, in accordance with an embodiment of the invention.

FIG. 2A is a diagram illustrating an exemplary cellular sub-networkoperable to utilize intelligent frequency and/or channel selection toreduce interference, in accordance with an embodiment of the invention.

FIG. 2B is a diagram illustrating an exemplary cellular sub-networkcomprising one or more femtocells operable to utilize intelligentfrequency and/or channel selection to reduce interference, in accordancewith an embodiment of the invention.

FIG. 2C is a diagram illustrating an exemplary cellular sub-networkcomprising femtocells operable to utilize intelligent frequency and/orchannel selection to reduce interference, in accordance with anembodiment of the invention.

FIG. 3 is a flow chart illustrating exemplary steps for utilizingintelligent frequency and/or channel selection to reduce interference,in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention may be found in a method and systemfor mitigating interference among femtocells via intelligent channelselection. In various embodiments of the invention, signals which mayinterfere with cellular communications between a femtocell and acellular enabled communication device may be detected. Based on thedetection, the femtocell may be configured to transmit and/or receivesignals on one or more frequencies and/or channels. The femtocell maydetect the interference signals by measuring, for example, receivedsignal strength, SNR, SINR, and CNR. The one or more frequencies and/orchannels may be determined in the femtocell and/or in a networkmanagement entity. Frequencies and/or channels determined in a networkmanagement entity may be communicated to the femtocell. Detectinginterfering signals and configuring of the femtocell may occurperiodically, upon installation of the femtocell, upon power-up of thefemtocell, and/or upon command from a network administrator.Communication between the femtocell and the network management entitymay be over an IP network. In various embodiments of the invention, theinterfering signals may be detected via one or more of a plurality offemtocells. In such instances, the results of the detection may becommunicated among the plurality of femtocells and/or with the networkmanagement entity.

FIG. 1A is a diagram illustrating an exemplary cellular network, inaccordance with an embodiment of the invention. Referring to FIG. 1A,there is shown a cellular network 100 comprising sub-networks 101 a-101c. The exemplary sub-network 101 a may comprise a base station 102,femtocells 110 a-110 d, which are collectively referred to herein asfemtocells 110, and cellular enabled communication devices 112 a and 112c, which are collectively referred to herein as cellular enabledcommunication devices 112. The femtocells 110 may be installed in one ormore commercial properties 104, one or more residential properties 106,and/or one or more multi-tenant properties 108.

The commercial properties 104 may comprise, for example, stores,restaurants, offices, and municipal buildings. The residentialproperties 106 may comprise, for example, single-family homes, homeoffices, and/or town-houses. Multi-tenant properties 108 may compriseresidential and/or commercial tenants such as apartments, condos,hotels, and/or high rises.

The base station 102 may be operable to communicate data wirelesslyutilizing one or more cellular standards such as IS-95, CDMA, GSM, TDMA,GPRS, EDGE, UMTS/NCDMA, TD-SCDMA, HSDPA, extensions thereto, and/orvariants thereof. “Data,” as utilized herein, may refer to any analogand/or digital information including but not limited to voice, Internetdata, and/or multimedia content. Multimedia content may comprise audioand/or visual content comprising, video, still images, animated images,and/or textual content. The base station 102 may communicate withcellular enabled communication devices such as the cellular enabledcommunication devices 112. Exemplary cellular standards supported by thebase station 102 may be specified in the International MobileTelecomunnications-2000 (IMT-2000) standard and/or developed by the3^(rd) generation partnership project (3GPP) and/or the 3^(rd)generation partnership project 2 (3GPP2). The base station 102 maycommunicate data amongst the various components of the sub-network 101a. Additionally, data communicated to and/or from the base station 102may be communicated to sub-network 101 b, sub-network 101 c, and/or toone or more other networks (not shown) via one or more backhaul links103. In this manner, data communicated to and/or from the base station102 may be communicated to and/or from, other portions of the network100 and/or other networks. Exemplary networks with which data may becommunicated may comprise public switched telephone networks (PSTN)and/or IP networks such as the Internet or an intranet.

The femtocells 110 may each comprise suitable logic, circuitry, and/orcode that may be operable to communicate wirelessly utilizing one ormore cellular standards such as IS-95, CDMA, GSM, TDMA, GPRS, EDGE,UMTS/NCDMA, TD-SCDMA, HSDPA, extensions thereto, and/or variantsthereof. In this regard, the femtocells 110 may each communicate withcellular enabled communication devices such as the cellular enabledcommunication devices 112. Exemplary cellular standards supported by thefemtocells 110 may be specified in the International MobileTelecomunnications-2000 (IMT-2000) standard and/or developed by the3^(rd) generation partnership project (3GPP) and/or the 3^(rd)generation partnership project 2 (3GPP2). Additionally, the femtocells110 may each comprise suitable logic, circuitry, and/or code that may beoperable to communicate over an IP network (not shown in FIG. 1A).

The cellular enabled communication devices 112 may each comprisesuitable logic, circuitry, and/or code that may be operable tocommunicate utilizing one or more cellular standards. In this regard,the cellular enabled communication devices 112 may each be operable totransmit and/or receive data via the cellular network 100. Exemplarycellular enabled communication device may comprise laptop computers,mobile phones, and personal media players. The cellular enabledcommunication devices 112 may be enabled to receive, process, andpresent multimedia content and may additionally be enabled run a networkbrowser or other applications for providing Internet services to a userof the cellular enabled communication device 112.

In operation, the cellular enabled communication devices 112 may gainaccess to the cellular network 100 and/or to other communicationnetworks via cellular communications with the base station 102 and thefemtocells 110. In this regard, in instances that a reliable connectionmay be established between the base station 102 and a cellular enabledcommunication device 112, then data may be communicated between thecellular enabled communication device 112 and the base station 102.Alternatively, in instances that a reliable connection may beestablished between a femtocell 110 and a cellular enabled communicationdevice 112, then data may be communicated between the cellular enabledcommunication device 112 and the femtocell 110. However, because of thefinite number of cellular channels and limited availability and cost oflicensing cellular frequencies, there may be a significant risk forinterference between two or more of the femtocells 110 and/or betweenone or more femtocells 110 and the base station 102. Thus, owners and/oroperators (owners/operators) of the femtocells 110 may desire and/orneed a way to mitigate the cellular interference caused by thefemtocells 110 in the cellular network 100.

Accordingly, aspects of the invention may enable characterizing anenvironment to detect interference and intelligently controlling afrequency and/or channel on which one or more of femtocells 110 transmitand/or receive cellular signals based on the detected interference.Intelligent control of frequencies and/or channels on which a femtocelltransmits and/or receives may enable reducing and/or minimizingoverlapping coverage areas of different femtocells and/or base stationsoperating on the same or closely spaced frequencies and/or channels.

FIG. 1B is a diagram illustrating cellular communication with via afemtocell, in accordance with an embodiment of the invention. Referringto FIG. 1B, there is shown a femtocell 144, cellular enabledcommunication devices 138 a and 138 b, collectively referred to hereinas cellular enabled communication devices 138, communication barrier142, and base station 146. The femtocell 144 may be communicativelycoupled to an IP network 132 via a link 134.

The base station 146 may be similar to or the same as the base station102 described with respect to FIG. 1A. The cellular enabledcommunication devices 138 may be similar to or the same as the cellularenabled communication devices 112 described with respect to FIG. 1A. Thefemtocell 144 may be similar to or the same as the femtocells 110described with respect to FIG. 1A.

The IP network 132 may comprise one or more network devices and/ornetwork links operable to transmit and/or receive IP packets. The IPnetwork 132 may provide access to the Internet and/or one or moreprivate networks.

The network management entity 133 may comprise suitable logic,circuitry, and/or code that may be operable to receive results ofenvironmental characterizations via one or more network links. Thecharacterization may comprise detecting potential interfering signals.The network management entity 264 may determine frequencies and/orchannels to be utilized by one or more femtocells based on the receivedinformation, and communicate the determination to the one or morefemtocells.

The link 134 may comprise a broadband link such as a digital subscriberline (DSL), passive optical network (PON), Ethernet, a T1/E1 line, acable television infrastructure, a satellite television infrastructure,and/or a satellite broadband Internet link. The link 134 may compriseone or more optical, wired, and/or wireless links.

The communications barrier 142 may comprise an obstruction to cellularcommunications. In some instances, the barrier 142 may comprise aphysical barrier such as a building or mountainous terrain. In someinstances, the barrier 142 may represent a distance which may be toogreat for reliable cellular communications. In some instances, thebarrier 142 may represent interference or a limitation of channelcapacity which may prevent cellular communications. The barrier 142 mayprevent cellular communications between the base station 146 and thecellular enabled communication device 138 a and may prevent cellularcommunications between the femtocell 144 and the cellular enabledcommunication device 138 b.

In operation, the cellular enabled communication device 138 a and thecellular enabled communication device 138 b may communicate via thefemtocell 144, the base station 146, and the IP network 132. Forexample, the cellular enabled communication device 138 a may transmitdata to the femtocell 144 utilizing one or more cellular standards. Thefemtocell 144 may packetize the data into one or more IP packets and theIP packets may be further encapsulated, encoded, modulated, or otherwiseprocessed. The IP packets may then be routed via the IP network 132 tothe base station 146. In some instances, the base station 146 mayutilize IP backloading and the IP packets may be conveyed to the basestation 146. In other instances, the IP packets may be transcoded viaone or more network elements (not shown in FIG. 1B) to a formatsupported by the base station 146. The data may then be extracted fromthe IP packets, transcoded to a format suitable for cellulartransmission, and subsequently transmitted to the cellular enabledcommunication device 138 b. In this manner, the femtocell 144 may enablecommunication with the cellular enabled communication device 138 a evenin instances that the cellular enabled communication device 138 a isunable to establish reliable cellular communications with a basestation. Because the femtocell 144 and the base station 146 areseparated by the barrier 142, they may operate on the same or closelyspaced frequencies and/or channels without interfering with one another.However, if the barrier 142 were not present, interference may arisebetween the cellular signals from the femtocell 144 and the cellularsignals from the base station 146. Accordingly, aspects of the inventionmay enable the femtocell 144 to characterize the environment in which itoperates to enable detection of interference from the base station 146or other sources and correspondingly adjusting a frequency and/orchannel on which it operates. A new frequency and/or channel ofoperation of the femtocell 144 may be controlled to be spaced as far aspossible from one or more frequencies and/or one or more channelsutilized by the base station 146 and/or of one or more other neighboringfemtocells and/or base stations.

Although, FIG. 1B describes communication between a pair of cellularenabled communication devices via a single femtocell and a base station,communication with other equipment via one or more femtocells and an IPnetwork may be similar to the communication described with respect toFIG. 1B. In this regard, devices which may communicate via one or morefemtocells may comprise cellular enabled communication devices in othersub-networks, cellular enabled communication devices in differentcellular networks, conventional “landline” phones coupled to a PSTN, IPphones, and computing devices such as PCs and fileservers coupled to anIP network.

FIG. 1C is a diagram illustrating an exemplary block diagram of afemtocell, in accordance with an embodiment of the invention. Referringto FIG. 1C, there is shown a femtocell 150 comprising an antenna 152, acellular transmitter and/or receiver (Tx/Rx) 154, a broadbandtransmitter and/or receiver (Tx/Rx) 156, a processor 158, a memory 160,and a digital signal processor (DSP) 162. The femtocell 150 may besimilar to or the same as the femtocells 110 described with respect toFIG. 1B.

The antenna 152 may be suitable for transmitting and/or receivingcellular signals. Although a single antenna is illustrated, theinvention is not so limited. In this regard, the cellular Tx/Rx 154 mayutilize a common antenna for transmission and reception, may utilizedifferent antennas for transmission and reception, and/or may utilize aplurality of antennas for transmission and/or reception.

The cellular Tx/Rx 154 may comprise suitable logic circuitry and/or codethat may be operable to transmit and/or receive voice and/or datautilizing one or more cellular standards. The cellular Tx/Rx 154 may beoperable to perform amplification, down-conversion, filtering,demodulation, and analog to digital conversion of received cellularsignals. The cellular Tx/Rx 154 may be operable to performamplification, up-conversion, filtering, modulation, and digital toanalog conversion of transmitted cellular signals. The cellular Tx/Rx154 may support communication over a plurality of communication channelsutilizing time division multiple access (TDMA) and/or code divisionmultiple access (CDMA). Exemplary cellular standards supported by thefemtocells 110 may be specified in the International MobileTelecomunnications-2000 (IMT-2000) standard and/or developed by the3^(rd) generation partnership project (3GPP) and/or the 3^(rd)generation partnership project 2 (3GPP2). The cellular Tx/Rx 154 may beoperable to transmit and/or receive on one or more frequencies and/orchannels. One or more of the frequencies and/or one or more of thechannels on which the cellular Tx/Rx 154 receives and/or transmits maybe configured via one or more control signals from the processor 158,memory 160, and/or the DSP 162. The cellular Tx/Rx 154 may also comprisea received signal strength indicator for characterizing an environmentin which the femtocell 150 resides.

The broadband Tx/Rx 156 may comprise suitable logic, circuitry, and/orcode that may be operable to transmit voice and/or data in adherence toone or more broadband standards. The broadband Tx/Rx 156 may be operableto perform amplification, down-conversion, filtering, demodulation, andanalog to digital conversion of received signals. The broadband Tx/Rx156 may be operable to perform amplification, up-conversion, filtering,modulation, and digital to analog conversion of transmitted signals. Invarious exemplary embodiments of the invention, the broadband Tx/Rx 156may transmit and/or receive voice and/or data over the link 157 whichmay be a T1/E1 line, optical fiber, DSL, cable televisioninfrastructure, satellite broadband internet connection, satellitetelevision infrastructure, and/or Ethernet. In various exemplaryembodiments of the invention, data received via the broadband Tx/Rx 156may be conveyed to the processor 158, memory 160, and/or the DSP 162 andmay be utilized to control one or more frequencies and/or channels onwhich the cellular Tx/Rx 154 transmits and/or receives.

The processor 158 may comprise suitable logic, circuitry, and/or codethat may enable processing data and/or controlling operations of thefemtocell 150. In this regard, the processor 158 may be enabled toprovide control signals to the various other blocks comprising thefemtocell 150. The processor 158 may also control data transfers betweenvarious portions of the femtocell 150. Additionally, the processor 158may enable execution of applications programs and/or code. In variousembodiments of the invention, the applications, programs, and/or codemay enable, for example, parsing, transcoding, or otherwise processingdata. In various embodiments of the invention, the applications,programs, and/or code may enable, for example, configuring orcontrolling operation of the cellular Tx/Rx 154, the broadband Tx/Rx156, the DSP 162, and/or the memory 160. In various embodiments of theinvention, the applications, programs, and/or code may enable detectinginterference and/or controlling cellular one or more frequencies and/orone or more channels on which the cellular Tx/Rx 154 transmits and/orreceives.

The memory 160 may comprise suitable logic, circuitry, and/or code thatmay enable storage or programming of information that includesparameters and/or code that may effectuate the operation of thefemtocell 150. The parameters may comprise configuration data and thecode may comprise operational code such as software and/or firmware, butthe information need not be limited in this regard. Moreover, theparameters may include adaptive filter and/or block coefficients.Additionally, the memory 160 may buffer or otherwise store received dataand/or data to be transmitted. In various embodiments of the invention,the memory 160 may comprise one or more look-up tables utilized fordetermining cellular enabled communication devices within a coveragearea of the femtocell 150. In various embodiments of the invention, thememory 160 may comprise one or more look-up tables or other datastructures which may comprise information controlling one or morefrequencies and/or one or more channels on which the cellular Tx/Rx 154transmits and/or receives.

The DSP 162 may comprise suitable logic, circuitry, and/or code operableto computationally intensive processing. In various embodiments of theinvention, the DSP 162 may encode, decode, modulate, demodulate,encrypt, and/or decrypt data. In various embodiments of the invention,the DSP 162 may be operable to detect interference and/or control one ormore frequencies and/or one or more channels on which the cellular Tx/Rx154 transmits and/or receives. The DSP 162 may be operable to perform,for example, fast Fourier transform analysis (FFT) of received signalsto characterize an environment in which the femtocell 150 resides.

In an exemplary embodiment of the invention, the femtocell 150 maycharacterize its environment by receiving signals on one or morefrequencies and/or channels via the cellular Tx/Rx 154, conveying thereceived signals to the DSP 162, and performing one or more measurementsand/or calculations on the signals via the DSP 162. In this regard, theDSP may characterize received signals utilizing metrics such as in-bandinterference, out-of-band interference, and/or signal-to-noise ratio(e.g. SNR, SINR, CNR). The characterization may enable detection ofinterfering signals. Results of the characterization may be conveyed tothe processor 158 and/or stored in the memory 160 and may be utilized,at least in part, to determine one or more frequencies and/or channelson which the cellular Tx/Rx 154 may transmit and/or receive. In thismanner, interference may be reduced. The results of the characterizationmay be communicated over, for example, an IP network to which they andthe femtocell 150 are communicatively coupled via the broadband Tx/Rx156.

The one or more frequencies and/or channels on which the cellular Tx/Rx154 may transmit and/or receive may also be determined, at least inpart, based on data received via the broadband Tx/Rx 156. In thisregard, other femtocells and/or base stations may characterize theenvironment in which they are operating and may communicate results ofthose characterizations over, for example, an IP network to which theyand the femtocell 150 are communicatively coupled. In variousembodiments of the invention, characterizing an environment may comprisemeasuring signal strengths on one or more frequencies and/or channelsand perform one or more calculations and/or analyses utilizing themeasurements. In this manner, signals which may interfere with cellularcommunications with the femtocell 150 may be detected.

In other embodiments of the invention, the femtocell 150 may communicateresults of the characterization to a network management entity, such asthe network management entity 133 described with respect to FIG. 1B. Thenetwork management entity may utilize the information received from thefemtocell 150 to determine frequencies and/or channels on which thefemtocell 150 should transmit and/or receive. Additional and/oralternatively, the network management entity 133 may utilizecharacterization results received from other base stations and/orfemtocells to determine frequencies and/or channels on which thefemtocell 150 should transmit and/or receive. In this regard, the otherbase stations and/or femtocells may have coverage areas that maypotentially overlap with the coverage area of the femtocell 150.

FIG. 2A is a diagram illustrating an exemplary cellular sub-networkoperable to utilize intelligent frequency and/or channel selection toreduce interference, in accordance with an embodiment of the invention.Referring to FIG. 2A, there is shown a sub-network 200 comprising a basestation 206 and femtocells 202 a, 202 b, and 202 c, collectivelyreferred to as femtocells 202.

The base station 206 may be similar to or the same as the basestation(s) 102 of FIG. 1A and/or the base station 146 of FIG. 1B. Thebase station 206 may have a coverage area 208, which although depictedas elliptical, is not limited with regard to a particular size, shape,or directionality.

The femtocells 202 may be similar to or the same as the femtocells 110of FIG. 1A, the femtocell 144 of FIG. 1B, and/or the femtocell 150 ofFIG. 1C. The femtocells 202 a and 202 b may have coverage areas 204 aand 204 b, respectively. Although the coverage areas 204 a and 204 b aredepicted as being elliptical, the invention is not so limited.Accordingly, the coverage area 204 a and 204 b are not limited withregard to a particular size, shape, or directionality.

The top half of FIG. 2A shows the sub-network 200 prior to time instantT1 and the bottom half of FIG. 2A shows the sub-network 200 after timeinstant T1.

Prior to time instant T1, the femtocell 202 c may not be transmittingcellular signals. In this regard, the femtocell 202 c may, for example,have just been installed and/or powered up. However, prior to timeinstant T1, the femtocell 202 c may measure received signal strength tocharacterize an environment in which it is operating. In this manner,the femtocell 202 c may determine the potential of interference fromother femtocells, base stations, and/or other sources. In this regard,in the exemplary sub-network 200, the femtocell 202 c may be within thecoverage area 208 of the base station 206, the coverage area 204 a ofthe femtocell 202 a, and the coverage area 204 b of the femtocell 202 b.The measured signal levels may be utilized to determine one or morefrequencies and/or channels on which the femtocell may transmit and/orreceive with tolerable levels of interference.

Subsequent to time instant T1, the femtocell 202 c may begin providingcellular services. In this regard, after time instant T1 the femtocell202 c may be operable communicate on the channels and/or frequenciesdetermined prior to time instant T1 with one or more cellular enabledcommunication devices within its coverage area 204 c. Although thecoverage area 204 c is depicted as elliptical, the invention is not solimited. Accordingly, the coverage area 204 c is not limited to aparticular size, shape, or directionality.

In an exemplary embodiment of the invention, there may be 5 frequenciesavailable for cellular communication. The base station 206 may becommunicating on frequency 5, the femtocell 202 b may be communicatingon frequency 4, and the femtocell 202 a may be communicating onfrequency 3. Accordingly, prior to time instant T1 the femtocell 202 cmay detect the frequencies being utilized and may determine thatfrequency 1 is the best frequency on which it should communicate inorder to minimize interference with nearby devices. In this manner, thefemtocell 202 b may provide cellular service to cellular enabledcommunication devices within the coverage area 204 c.

FIG. 2B is a diagram illustrating an exemplary cellular sub-networkcomprising one or more femtocells operable to utilize intelligentfrequency and/or channel selection to reduce interference, in accordancewith an embodiment of the invention. Referring to FIG. 2B, there isshown a sub-network 220 comprising a base station 226 and femtocells 222a, 222 b, and 222 c, collectively referred to as femtocells 222. Thefemtocells 222 and the base station 226 may be communicatively coupledvia network links 230.

The base station 226 may be similar to or the same as the basestation(s) 206 of FIG. 2A. The base station 226 may have a coverage area228, which, although depicted as elliptical, is not limited with regardto size, shape, or directionality.

The femtocells 222 may be similar to or the same as the femtocells 202of FIG. 2A. The femtocells 222 a and 222 b may have coverage areas 224 aand 224 b, respectively. Although the coverage areas 224 a and 224 b aredepicted as elliptical, they are not limited with regard to size, shape,or directionality.

The network links 230 may comprise wired or wireless links similar to orthe same as the links 134 and 135 of FIG. 1B.

The left half of FIG. 2B shows the sub-network 220 prior to time instantT1 and the right half of FIG. 2B shows the sub-network 220 after to timeinstant T1.

Prior to time instant T1, the femtocell 222 c may not be transmittingcellular signals. In this regard, the femtocell 222 c may, for example,have just been installed and/or powered up. In the exemplary sub-network220, the femtocell 222 c may be within the coverage area 228 of the basestation 226, the coverage area 224 a of the femtocell 222 a, and thecoverage area 224 b of the femtocell 222 b. Prior to time instant T1,the femtocell 222 c may characterize the environment in which it residesto detect potential interference from other femtocells, base stations,and/or other sources. Similarly, in addition to engaging in cellularcommunications, one or more of the femtocell 222 a, the femtocell 222 b,and the base station 226 may also characterize the environment in whichthey are operating to detect interfering signals from other femtocells,base stations, and/or other sources.

The results of the characterization may be communicated between two ormore of the femtocell 222 a, the femtocell 222 b, the femtocell 222 c,and the base station 226. In this manner, one or more of the femtocell222 a, the femtocell 222 b, the femtocell 222 c, and the base station226 may utilize characterization results received from other nodes todetermine which frequencies and/or channels on which to transmit and/orreceive cellular signals. In various embodiments of the invention, thebase station 226 and each of the femtocells 222 may be part of ahierarchy and frequencies may first be chosen to reduce interference atnodes higher up in the hierarchy and then, if possible, reduceinterference at nodes that are lower in the hierarchy.

After time instant T1, the femtocell 222 c may begin providing cellularservices. In this regard, after time instant T1 the femtocell 222 c maybe operable to communicate with one or more cellular enabledcommunication devices within its coverage area 224 c on the channelsand/or frequencies determined prior to time instant T1. Although thecoverage area 224 c is depicted as elliptical, the invention is not solimited. Accordingly, the coverage area 224 c is not limited to aparticular size, shape, and/or directionality.

In an exemplary embodiment of the invention, there may be 5 channelsavailable for cellular communication. The base station 226 may becommunicating on channel 1, the femtocell 222 b may be communicating onchannel 2, and the femtocell 222 a may be communicating on channel 1. Inthis regard, prior to time instant 1, there may be interference betweenthe base station 226 and the femtocell 222 a in places where theircoverage areas overlap. Accordingly, prior to time instant T1, thefemtocell 222 c may detect that the base station 226 and the 222 a areboth communicating on cellular channel 1 and that the femtocell iscommunicating on cellular channel 2. The femtocell 222 c may communicatethis information to the femtocell 222 a and the base station 226.Consequently, additional messages may be communicated between thefemtocells 222 and the base station 226 in order to determine a channelfor each node to communicate on in order to optimize interference levelsin the sub-network 220. For example, various in band and/or out-of-band(OOB) messages communicated between the various nodes 222 and 226 of thesub-network 220 may result in the femtocell 222 a switching to channel 3and the femtocell 222 c operating on channel 5.

FIG. 2C is a diagram illustrating an exemplary cellular sub-networkcomprising femtocells operable to utilize intelligent frequency and/orchannel selection to reduce interference, in accordance with anembodiment of the invention. Referring to FIG. 2C, there is shown asub-network 250 comprising a base station 256 and femtocells 252 a, 252b, and 252 c, collectively referred to as femtocells 252. The femtocells252 and the base station 256 may be communicatively coupled to a networkmanagement entity 264 via network links 260.

The base station 256 may be similar to or the same as the basestation(s) 206 of FIG. 2A. The base station 256 may have a coverage area258, which, although depicted as being elliptical, is not limited withregard to a particular size, shape, or directionality.

The femtocells 252 may be similar to or the same as the femtocells 202of FIG. 2A. The femtocells 252 a and 252 b may have coverage areas 254 aand 254 b, respectively. Although the coverage areas 254 a and 254 b aredepicted as elliptical, they are not limited with regard to a particularsize, shape, or directionality.

The network links 260 may comprise wired or wireless links similar to orthe same as the links 134 and 135, which are described with respect toFIG. 1B.

The network management entity 264 may be similar to or the same as thenetwork management entity 133 described with respect to FIG. 1B.

The left half of FIG. 2C shows the sub-network 250 prior to time instantT1 and the right half of FIG. 2C shows the sub-network 250 after to timeinstant T1.

In the exemplary sub-network 250, the femtocell 252 c may be within thecoverage area 258 of the base station 256, the coverage area 254 a ofthe femtocell 252 a, and the coverage area 254 b of the femtocell 202 b.Prior to time instant T1, the femtocell 252 c may not be transmittingcellular signals. In this regard, the femtocell 252 c may, for example,have just been installed and/or powered up. The femtocell 252 c maymeasure received signal strength to characterize the environment anddetect potential interference from other femtocells, base stations,and/or other sources. The femtocell 252 b may communicate results of thecharacterization to the network management entity 264. Similarly, inaddition to engaging in cellular communications, one or more of thefemtocell 252 a, the femtocell 252 b, and the base station 256 may alsocharacterize the environment in which they are operating and communicateresults of the characterization to the network management entity 264.

The network management entity 264 may utilize signal measurements and/orinformation associated therewith from one or more of the femtocell 252a, the femtocell 252 b, the femtocell 252 c, and the base station 256 todetermine frequencies and/or channels to be utilized by the variousnodes. In this manner, the network management entity 264 may determinethe frequencies and/or channels of operation for the various nodes 254and 256 in order to minimize interference in the sub-network 250. Invarious exemplary embodiments of the invention, the base station 256 andeach of the femtocells 252 may be part of a hierarchy and frequenciesmay first be chosen to minimize interference at nodes higher up in thehierarchy and then, if possible, reduce interference at nodes that arelower in the hierarchy. Other schemes may be utilized without departingfrom the spirit and/or scope of the invention.

Prior to time instant T1, the network management entity 264 maycommunicate the frequency and/or channel determinations to the variousnodes, femtocell 222 a, the femtocell 222 b, the femtocell 222 c, andthe base station 226, of the sub-network 250. Each of the femtocells 222may configure one or more channels and/or frequencies on which ittransmits and/or receives cellular signals.

After time instant T1, the femtocells 222 may be configured and maybegin providing cellular services. Thus, the femtocells 252 a, 252 b,and 252 c may be operable to communicate with one or more cellularenabled communication devices within their respective coverage areas 254a, 254 b, and 254 c on the channels and/or frequencies determined priorto time instant T1. In this regard, the coverage areas 254 a, 254 b, and254 c are depicted as elliptical. Notwithstanding, the coverage areas254 a, 254 b, and 254 c are not limited with regard to a particularsize, shape, or directionality.

In an exemplary embodiment of the invention, there may be 5 frequenciesavailable for cellular communication. The base station 256 may becommunicating on frequency 1, the femtocell 252 b may be communicatingon frequency 2, and the femtocell 252 a may be communicating onfrequency 1. Prior to T1, the femtocell 252 a may communicate that it isoperating on frequency 1 to the network management entity, the femtocell252 b may communicate to the network management entity that it isoperating on frequency 2, and the base station 256 may communicate anindication to the network management entity to specify that it isoperating on frequency 1. Additionally, each of the femtocells 252 andthe base station 256 may also communicate signal measurements and/orinformation associated therewith to the network management entity 264.Accordingly, the femtocell 252 c may detect that the base station 256and the 252 a are both communicating on cellular frequency 1 and it maycommunicate to the network management entity 264 that the base station256 and the femtocell 252 a are interfering with each other in at leasta portion of their coverage areas. The network management entity 264 mayutilize the information received from various nodes to reconfigure thefemtocell 252 to operate on frequency 3 and for the femtocell 252 c tooperate on frequency 5.

FIG. 3 is a flow chart illustrating exemplary steps for utilizingintelligent frequency and/or channel selection to reduce interference,in accordance with an embodiment of the invention. Referring to FIG. 3,the exemplary steps may begin with step 302 when a femtocell may beinstalled and/or powered-up. In other exemplary embodiments of theinvention, the exemplary steps of FIG. 3 may be performed periodicallyor on command from a network administrator. Subsequent to step 320, theexemplary steps may advance to step 304.

In step 304, the femtocell powered up in step 302 may characterize itsenvironment in order to detect potential interference from otherfemtocells, base stations, or other sources. The femtocell may besimilar to or the same as the femtocell 150 in FIG. 1C in that it maycomprise a cellular Tx/Rx, a DSP, a memory, and a baseband processor forcharacterizing an environment in which it resides. In this regard, thefemtocell 150 may measure signal strengths and perform one or morecalculations and/or analyses utilizing the measurements. Subsequent tostep 304, the exemplary steps may advance to step 306.

In step 306, it may be determined whether the femtocell is in a networkmanaged by a network management entity. In instances that the network isnot managed by a network management entity, the exemplary steps mayadvance to step 308.

In step 308, the femtocell may utilize the results of thecharacterization to determine one or more frequencies and/or channels onwhich it should transmit and/or receive cellular signals. In thisregard, one or more frequencies and/or one or more channels may bechosen in an attempt to minimize interference with other femtocellsand/or base stations. In some instances, the frequencies and/or channelsmay be chosen based in part on characterizations performed by other basestations and/or femtocells in the network. In this regard, the femtocellmay be similar to the femtocell 150 of FIG. 1C in that it may comprise abroadband Tx/Rx enabled to communicate over non-cellular networks suchas an IP network. Subsequent to step 308, the exemplary steps mayadvance to step 310.

In step 310, the femtocell may be configured to operate on the one ormore frequencies and/or channels determined in step 310. For example, aprocessor, memory, and/or DSP of the femtocell may provide one or morecontrol signals to configure a cellular Tx/Rx of the femtocell.Subsequent to step 310, the exemplary steps may advance to step 312.

In step 312, the femtocell may begin supporting cellular communicationsfor one or more cellular enabled communication devices within itscoverage area.

Returning to step 306, in instances that the network is managed by anetwork management entity, the exemplary steps may advance to step 314.

In step 314, the femtocell may communicate results of thecharacterization of step 304 to a network management entity. In thisregard, the femtocell may communicate with the network management entityvia a non-cellular connection such as an IP connection. Subsequent tostep 314, the exemplary steps may advance to step 316.

In step 316, the network management entity may determine one or morefrequencies and/or channels for femtocell to transmit and/or receivecellular signals on. In this regard, the frequencies and/or channels maybe chosen so as to minimize interference with other femtocells and/orbase stations. In some instances, the frequencies and/or channels may bechosen based, at least in part, on characterizations performed by otherbase stations and/or femtocells in the network. Subsequent to step 316,the exemplary steps may advance to step 318.

In step 318, the network management entity may communicate one or moremessages to the femtocell indicating a frequency and/or channel for thefemtocell to transmit and/or received cellular signals on. Additionally,the network management entity may communicate one or more messages toother femtocells and/or base stations in the network informing them ofthe determination and/or indicating they should switch to a differentfrequency and/or channel.

Aspects of a method and system for mitigating interference amongfemtocells via intelligent channel selection are provided. In anexemplary embodiment of the invention, signals which may interfere withcellular communications between a femtocell 110 a and a cellular enabledcommunication device 112 may be detected. Based on the detection, thefemtocell 112 may be configured to transmit and/or receive signals onone or more frequencies and/or channels. The femtocell 112 may detectthe interference signals by measuring, for example, received signalstrength, SNR, SINR, and CNR. The one or more frequencies and/orchannels may be determined in the femtocell 112 and/or in a networkmanagement entity 264. Frequencies and/or channels determined in thenetwork management entity 264 may be communicated to the femtocell 112.Detecting interfering signals and configuring of the femtocell 112 mayoccur periodically, upon installation of the femtocell 112, uponpower-up of the femtocell 112, and/or upon command from a networkadministrator. Communication between the femtocell and the networkmanagement entity may be over an IP network. In another embodiment ofthe invention, the interfering signals may be detected via one or moreof a plurality of femtocells 222 a-222 c. In such instances, the resultsof the detection may be communicated among the plurality of femtocells222 a-222 c and/or with the network management entity 264.

Another embodiment of the invention may provide a machine and/orcomputer readable storage and/or medium, having stored thereon, amachine code and/or a computer program having at least one code sectionexecutable by a machine and/or a computer, thereby causing the machineand/or computer to perform the steps as described herein for mitigatinginterference among femtocells via intelligent channel selection.

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in at least onecomputer system, or in a distributed fashion where different elementsare spread across several interconnected computer systems. Any kind ofcomputer system or other apparatus adapted for carrying out the methodsdescribed herein is suited. A typical combination of hardware andsoftware may be a general-purpose computer system with a computerprogram that, when being loaded and executed, controls the computersystem such that it carries out the methods described herein.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

1. A method for communication, the method comprising: detecting presenceof signals that will interfere with cellular communications between afemtocell and a cellular enabled communication device that communicateswith said femtocell, and configuring said femtocell to transmit and/orreceive cellular signals on one or more frequencies and/or channels,wherein said one or more frequencies and/or channels are determinedbased on said results of said detection.
 2. The method according toclaim 1, comprising detecting said presence of said signals by measuringreceived signal strength on one or more frequencies.
 3. The methodaccording to claim 1, comprising detecting said presence of said signalsby measuring received signal strength on one or more channels.
 4. Themethod according to claim 1, comprising determining said one or morefrequencies and/or channels in said femtocell.
 5. The method accordingto claim 1, comprising determining said one or more frequencies and/orchannels in a network management entity.
 6. The method according toclaim 5, wherein said one or more frequencies and/or channels arecommunicated from said network management entity to said femtocell. 7.The method according to claim 1, comprising performing said detectingand said configuring upon installing and/or powering up said femtocell.8. The method according to claim 1, comprising performing said detectingand said configuring upon command from a network administrator.
 9. Themethod according to claim 1, comprising periodically performing saiddetecting and said configuring.
 10. The method according to claim 1,comprising communicating results of said detecting via an IP network.11. The method according to claim 1, comprising detecting said presenceof said signals via one or more of a plurality of femtocells.
 12. Themethod according to claim 11, comprising communicating results of saiddetection to a network management entity and/or among said plurality offemtocells.
 13. A system for communication, the system comprising: oneor more circuits for use in a femtocell, wherein said one or morecircuits operable to: detect a presence of signals which will interferewith cellular communications between a femtocell and a cellular enabledcommunication device that communicates with said femtocell; andconfigure said femtocell to transmit and/or receive cellular signals onone or more frequencies and/or channels, wherein said one or morefrequencies and/or channels are determined based on said results of saiddetection.
 14. The system according to claim 13, wherein said one ormore circuits are operable to detect said presence of said signals bymeasuring received signal strength on one or more frequencies.
 15. Thesystem according to claim 13, wherein said one or more circuits areoperable to detect said presence of said signals by measuring receivedsignal strength on one or more channels.
 16. The system according toclaim 13, wherein said one or more circuits are operable to determinesaid one or more frequencies and/or channels.
 17. The system accordingto claim 13, wherein said one or more frequencies and/or channels aredetermined in a network management entity.
 18. The system according toclaim 17, wherein said one or more circuits are operable to receive saidone or more frequencies and/or channels from said network managemententity.
 19. The system according to claim 13, wherein said one or morecircuits are operable to perform said detecting and said configuringupon installing and/or powering up said femtocell.
 20. The systemaccording to claim 13, wherein said one or more circuits are operable toperform said detecting and said configuring upon initialization by anetwork administrator.
 21. The system according to claim 13, whereinsaid one or more circuits are operable to periodically perform saiddetecting and said configuring.
 22. The system according to claim 13,wherein said one or more circuits are operable communicate results ofsaid detecting via an IP network.
 23. The system according to claim 13,wherein said one or more circuits detect said presence of said signalsvia one or more of a plurality of femtocells.
 24. The system accordingto claim 23, comprising communicating results of said detection to anetwork management entity and/or among said plurality of femtocells.